Production of artificial filaments



ummm

. E'. KINSELLA mm.4

RODUCTION- OF ARTIFICIAL FILAMENTS Filed Nov. 2. 1955 Patented Apr. 30, 1935 UNITED STATES PATihl'i" FFIQE Edward Kinsella and Spenden,

Charles Wesley Addy,

near Derby, England, assignors to Celanese Corporation of America, a corporation of Delaware Application November En Great Britain 6 Claims.

This invention relates to the production of artincial materials and is particularly concerned with the manufacture of articial laments by the dry or evaporative method. The invention relates especially to the control of the conditions obtaining during the dry spinning operation.

in the spinning of artificial iilaments by the dry or evaporative method, the nature and iorm of the filaments produced depends to a large extent upon the spinning conditions, such as the rate oi" .flow and the temperature of the evaporative medium into which the filaments are extruded, the proportion oi' solvent present in such evaporative medium, the speed of extrusion of the spinning solution and the temperature of the spinning solution immediately prior to extrusion, and it is an object of the present invention to provide a simple and convenient method of controlling the last of these factors, that is, theV temperature of extrusion.

According to the present invention the spinning solution on its Way to the point of extrusion is passed through a pipe which is exposed to an adjustable extent to the atmosphere Within the spinning cell, and the temperature of the spinning solution in the pipe is controlled by adjusting the amount of such exposure. The temperature of the spinning solution is brought nearer to that of the evaporative atmosphere by heat exchange therewith, and the amount by which the temperature is changed in this manner is controlled by controlling the area available for such heat exchange. So long as the temperature of the spinning soiution'is diierent from that of the evaporative medium the control over the rate of heat exchange is effective. The temperature of the spinning solution prior to extrusion is affected by the rate of flow of the spinning solution. The present invention not only enables any desired temperature or spinning solution to be obtained with a given speed of spinning, but also enables a given temperature to be maintained whatever the speed of spinning, thus counteracting the eiect which varying the spinning speed has upon the temperature of the spinning solution.

A convenient means for carrying out the invention comprises a coiled pipe through which the spinning solution is allowed to pass, together with an insulating shield surrounding such pipe and enabling the area of the pipe exposed to the evaporative medium to be varied. The shield may be a plain cylinder, or it may be closed at one end, a suitable perforation being left at the the spinning solution prior to 2, i933, Serial No. 696,376

November 23, 1932 closed end for a straight extension of the coil to pass through. A particularly convenient a1'- rangenient makes use of the lter candle usually employed to lter the spinning solution prior to extrusion. The candle is a cylindrical body, and the coil through which the spinning solution is passed is wound closely round the candle, the spinning solution passing through it eitherbefore or after entering the lter candle. The candle protects the inside of the coil from contact with the evaporative medium, leaving only the outside of the coil to be surrounded by a plain cylindrical insulating shield, adjustable for the desired control. It is preferred that the materal of which the coil pipe is constructed should be of high conductivity, while the material of which the shield is constructed is of low conductivity. In addition the pipe is preferably of such form as to have a large surface in comparison with its cross section, and such surface may be corrugated or otherwise formed so as to absorb heat at a relatively high rate, while the material of the shield may be such as to preventl heat frombeing absorbed. Thus, a non-con-f ducting asbestos shield may be employed.

By feeding the spinning solution to the coil at a temperature lower than the temperature of the evaporative atmosphere, to which the coil is subjected within the cell, the spinning solution may be raised to any temperature up to the neighborhood of the temperature of the atmosphere. Since in spinning the iilaments are usually extruded downwardly into a heated cell, the upper part of the cell, at which the spinning jet lies, is at a high temperature, on account of convection. For this reason, the spinning solution entering the cell will ordinarily be at a lower temperature than the air. Provided that there is a temperature diiierence between the spinning solution and the air, the temperature of the spinning solution can be controlled bythe ccntrol of the area of coil exposed. Further control may be effected by varying the length and the bore of the coil, whereby the solution is exposed for a greater or shorter time to the action of the air.

The accompanying drawing illustrates, by way of example, one form of apparatus according to the invention.

Figure 1 is a side elevation in section of a spinning cell provided with the apparatus; and

Figure 2 is a part-sectional elevation showing details of Figure 1.

In Figure l a spinning cell 3, the atmosphere in which is heated by heating pipes d, is pro- 2 vided with a filter candle 5 carrying an adapter 6 to Which the spinning jet 'l is tted. The filter candle 5 is sheathed to an adjustable extent by a split asbestos jacket 8, the position of which on the candle can be fixed by tightening the metal band 9 surrounding the jacket by means of the screw Il] which causes the jacket to grip the candle.

As shown in Figure 2 the spinning solution passes through the candle 5 into the adapter 6 and then up the pipe il lying along the outside of the candle and through the coil i2 which is Wound round the candle, back to the adapter 6 and thence to the spinning jet 1, loss of heat from the heated solution proceeding to the jet being minimized by an asbestos insulating layer I3 in the adapter f5.

Although the invention nds its principal application in connection With dry spinning of cellulose acetate solutions in air, it is not limited to any particular dry spinning process. It may, for example, be applied in dry spinning solutions of cellulose formate, propionate and butyrate or other cellulose ester or ethyl, methyl or benzyl cellulose or other cellulose ether or Oxy-ethyl cellulose acetate or other mixed ether-ester of cellulose.

The apparatus may be used in the production of threads exhibiting differential lustre eiects by reason of different laments in the thread having been spun from solutions at diierent temperatures. In order to adapt the apparatus for this purpose, two or more candles in the same cell or in diierent cells have their insulating jackets adjusted to diierent temperatures. The lustre oi the filaments varying in accordance with the temperature oi the solution, the filaments issuing from the different jets may combine in any desired proportion to forni thread showing corresponding diferences in lustre.

What We claim and desire to secure by Letters Patent is:-

l. Apparatus for attemperating the spinning solution in the production of artificial filaments by dry spinning methods, comprising a body through Which the spinning solution passes and adapted to be exposed to the atmosphere of the spinning cell, and a shield Which is adjustable with respect to the body so as to regulate the extent to which the body is exposed to the atmosphere oi the spinning cell. v

2. Apparatus for attemperating the spinning solution in the production of artificial filaments by dry spinning methods, comprising a coil through which the spinning solution passes and which is adapted to be exposed to the atmosphere of the spinning cell, and a shield which is adjustable with respect to the coil so as to regulate the extent to which the coil is exposed to the atmosphere of the spinning cell. Y

3. Apparatus according to claim 2 wherein the coil is cylindrical and the amount of the coil to be exposed is adjusted by means of a cylindrical shield surrounding and slidable With respect to the coil.

4. Apparatus for' attemperating the spinning solution in the production o articial filaments by dry spinning methods, comprising a lter, a cylindrical coil surrounding said filter and adapted to be exposed to the atmosphere of the spinning cell, said filter and said coil being connected in series for the passage of the spinning solution, and a cylindrical shield surrounding said coil and slidable with respect thereto so as to regulate the extent to which the to the atmosphere of the spinning cell.

5. Apparatus according to claim 4, wherein the coil and filter are so connected that the spinning solution passes iirst through the filter and then through the coil.

6. Apparatus according to claim 4, comprising an adapter tted to the lter, which adapter supports the spinning jet and is formed' with coil is exposedV passages providing connections between the filter 40 and the coil and the coil and the jet, respectively.

EDWARD KINSELLA. CHARLES WESLEY ADDY. 

